str1 = "hello world"
str2 = 'hello world'
str3 = """hello world"""
print(str1)
print(str2)
print(str3)
print('hel\'lo world')#\转义符
print('123---{0}----{1}----{2}'.format(4,5,6))
str1='hello'
print(f'123---{str1}')
# 显示进度
for i in range(0,101,2):
    print("========开始下载========")
    if i == 100:
        print("下载完成")
    else:
        str4 = "*"*(i//2) + "."*((100-i)//2)
        print(f'{i}%{str4}]')
